diff options
Diffstat (limited to 'poky/meta/recipes-devtools/gdb/gdb/0001-aarch64-Check-for-valid-inferior-thread-regcache-bef.patch')
| -rw-r--r-- | poky/meta/recipes-devtools/gdb/gdb/0001-aarch64-Check-for-valid-inferior-thread-regcache-bef.patch | 286 |
1 files changed, 0 insertions, 286 deletions
diff --git a/poky/meta/recipes-devtools/gdb/gdb/0001-aarch64-Check-for-valid-inferior-thread-regcache-bef.patch b/poky/meta/recipes-devtools/gdb/gdb/0001-aarch64-Check-for-valid-inferior-thread-regcache-bef.patch deleted file mode 100644 index 9adf4a4db5..0000000000 --- a/poky/meta/recipes-devtools/gdb/gdb/0001-aarch64-Check-for-valid-inferior-thread-regcache-bef.patch +++ /dev/null @@ -1,286 +0,0 @@ -From b3eff3e15576229af9bae026c5c23ee694b90389 Mon Sep 17 00:00:00 2001 -From: Luis Machado <luis.machado@arm.com> -Date: Fri, 24 Mar 2023 07:58:38 +0000 -Subject: [PATCH] aarch64: Check for valid inferior thread/regcache before - reading pauth registers - -Upstream-Status: Backport -Signed-off-by: Ross Burton <ross.burton@arm.com> - -There were reports of gdb throwing internal errors when calling -inferior_thread ()/get_current_regcache () on a system with -Pointer Authentication enabled. - -In such cases, gdb produces the following backtrace, or a variation -of it (for gdb's with the non-address removal implemented only in -the aarch64-linux-tdep.c file). - -../../../repos/binutils-gdb/gdb/thread.c:86: internal-error: inferior_thread: Assertion `current_thread_ != nullptr' failed. -A problem internal to GDB has been detected, -further debugging may prove unreliable. ------ Backtrace ----- -0xaaaae04a571f gdb_internal_backtrace_1 - ../../../repos/binutils-gdb/gdb/bt-utils.c:122 -0xaaaae04a57f3 _Z22gdb_internal_backtracev - ../../../repos/binutils-gdb/gdb/bt-utils.c:168 -0xaaaae0b52ccf internal_vproblem - ../../../repos/binutils-gdb/gdb/utils.c:401 -0xaaaae0b5310b _Z15internal_verrorPKciS0_St9__va_list - ../../../repos/binutils-gdb/gdb/utils.c:481 -0xaaaae0e24b8f _Z18internal_error_locPKciS0_z - ../../../repos/binutils-gdb/gdbsupport/errors.cc:58 -0xaaaae0a88983 _Z15inferior_threadv - ../../../repos/binutils-gdb/gdb/thread.c:86 -0xaaaae0956c87 _Z20get_current_regcachev - ../../../repos/binutils-gdb/gdb/regcache.c:428 -0xaaaae035223f aarch64_remove_non_address_bits - ../../../repos/binutils-gdb/gdb/aarch64-tdep.c:3572 -0xaaaae03e8abb _Z31gdbarch_remove_non_address_bitsP7gdbarchm - ../../../repos/binutils-gdb/gdb/gdbarch.c:3109 -0xaaaae0a692d7 memory_xfer_partial - ../../../repos/binutils-gdb/gdb/target.c:1620 -0xaaaae0a695e3 _Z19target_xfer_partialP10target_ops13target_objectPKcPhPKhmmPm - ../../../repos/binutils-gdb/gdb/target.c:1684 -0xaaaae0a69e9f target_read_partial - ../../../repos/binutils-gdb/gdb/target.c:1937 -0xaaaae0a69fdf _Z11target_readP10target_ops13target_objectPKcPhml - ../../../repos/binutils-gdb/gdb/target.c:1977 -0xaaaae0a69937 _Z18target_read_memorymPhl - ../../../repos/binutils-gdb/gdb/target.c:1773 -0xaaaae08be523 ps_xfer_memory - ../../../repos/binutils-gdb/gdb/proc-service.c:90 -0xaaaae08be6db ps_pdread - ../../../repos/binutils-gdb/gdb/proc-service.c:124 -0x40001ed7c3b3 _td_fetch_value - /build/glibc-RIFKjK/glibc-2.31/nptl_db/fetch-value.c:115 -0x40001ed791ef td_ta_map_lwp2thr - /build/glibc-RIFKjK/glibc-2.31/nptl_db/td_ta_map_lwp2thr.c:194 -0xaaaae07f4473 thread_from_lwp - ../../../repos/binutils-gdb/gdb/linux-thread-db.c:413 -0xaaaae07f6d6f _ZN16thread_db_target4waitE6ptid_tP17target_waitstatus10enum_flagsI16target_wait_flagE - ../../../repos/binutils-gdb/gdb/linux-thread-db.c:1420 -0xaaaae0a6b33b _Z11target_wait6ptid_tP17target_waitstatus10enum_flagsI16target_wait_flagE - ../../../repos/binutils-gdb/gdb/target.c:2586 -0xaaaae0789cf7 do_target_wait_1 - ../../../repos/binutils-gdb/gdb/infrun.c:3825 -0xaaaae0789e6f operator() - ../../../repos/binutils-gdb/gdb/infrun.c:3884 -0xaaaae078a167 do_target_wait - ../../../repos/binutils-gdb/gdb/infrun.c:3903 -0xaaaae078b0af _Z20fetch_inferior_eventv - ../../../repos/binutils-gdb/gdb/infrun.c:4314 -0xaaaae076652f _Z22inferior_event_handler19inferior_event_type - ../../../repos/binutils-gdb/gdb/inf-loop.c:41 -0xaaaae07dc68b handle_target_event - ../../../repos/binutils-gdb/gdb/linux-nat.c:4206 -0xaaaae0e25fbb handle_file_event - ../../../repos/binutils-gdb/gdbsupport/event-loop.cc:573 -0xaaaae0e264f3 gdb_wait_for_event - ../../../repos/binutils-gdb/gdbsupport/event-loop.cc:694 -0xaaaae0e24f9b _Z16gdb_do_one_eventi - ../../../repos/binutils-gdb/gdbsupport/event-loop.cc:217 -0xaaaae080f033 start_event_loop - ../../../repos/binutils-gdb/gdb/main.c:411 -0xaaaae080f1b7 captured_command_loop - ../../../repos/binutils-gdb/gdb/main.c:475 -0xaaaae0810b97 captured_main - ../../../repos/binutils-gdb/gdb/main.c:1318 -0xaaaae0810c1b _Z8gdb_mainP18captured_main_args - ../../../repos/binutils-gdb/gdb/main.c:1337 -0xaaaae0338453 main - ../../../repos/binutils-gdb/gdb/gdb.c:32 ---------------------- -../../../repos/binutils-gdb/gdb/thread.c:86: internal-error: inferior_thread: Assertion `current_thread_ != nullptr' failed. -A problem internal to GDB has been detected, -further debugging may prove unreliable. -Quit this debugging session? (y or n) - -We also see failures across the testsuite if the tests get executed on a target -that has native support for the pointer authentication feature. But -gdb.base/break.exp and gdb.base/access-mem-running.exp are two examples of -tests that run into errors and internal errors. - -This issue started after commit d88cb738e6a7a7179dfaff8af78d69250c852af1, which -enabled more broad use of pointer authentication masks to remove non-address -bits of pointers, but wasn't immediately detected because systems with native -support for pointer authentication are not that common yet. - -The above crash happens because gdb is in the middle of handling an event, -and do_target_wait_1 calls switch_to_inferior_no_thread, nullifying the -current thread. This means a call to inferior_thread () will assert, and -attempting to call get_current_regcache () will also call inferior_thread (), -resulting in an assertion as well. - -target_has_registers was one function that seemed useful for detecting these -types of situation where we don't have a register cache. The problem with that -is the inconsistent state of inferior_ptid, which is used by -target_has_registers. - -Despite the call to switch_to_no_thread in switch_to_inferior_no_thread from -do_target_wait_1 in the backtrace above clearing inferior_ptid, the call to -ps_xfer_memory sets inferior_ptid momentarily before reading memory: - -static ps_err_e -ps_xfer_memory (const struct ps_prochandle *ph, psaddr_t addr, - gdb_byte *buf, size_t len, int write) -{ - scoped_restore_current_inferior restore_inferior; - set_current_inferior (ph->thread->inf); - - scoped_restore_current_program_space restore_current_progspace; - set_current_program_space (ph->thread->inf->pspace); - - scoped_restore save_inferior_ptid = make_scoped_restore (&inferior_ptid); - inferior_ptid = ph->thread->ptid; - - CORE_ADDR core_addr = ps_addr_to_core_addr (addr); - - int ret; - if (write) - ret = target_write_memory (core_addr, buf, len); - else - ret = target_read_memory (core_addr, buf, len); - return (ret == 0 ? PS_OK : PS_ERR); -} - -Maybe this shouldn't happen, or maybe it is just an unfortunate state to be -in. But this prevents the use of target_has_registers to guard against the -lack of registers, since, although current_thread_ is still nullptr, -inferior_ptid is valid and is not null_ptid. - -There is another crash scenario after we kill a previously active inferior, in -which case the gdbarch will still say we support pointer authentication but we -will also have no current thread (inferior_thread () will assert etc). - -If the target has support for pointer authentication, gdb needs to use -a couple (or 4, for bare-metal) mask registers to mask off some bits of -pointers, and for that it needs to access the registers. - -At some points, like the one from the backtrace above, there is no active -thread/current regcache because gdb is in the middle of doing event handling -and switching between threads. - -Simon suggested the use of inferior_ptid to fetch the register cache, as -opposed to relying on the current register cache. Though we need to make sure -inferior_ptid is valid (not null_ptid), I think this works nicely. - -With inferior_ptid, we can do safety checks along the way, making sure we have -a thread to fetch a register cache from and checking if the thread is actually -stopped or running. - -The following patch implements this idea with safety checks to make sure we -don't run into assertions or errors. If any of the checks fail, we fallback to -using a default mask to remove non-address bits of a pointer. - -I discussed with Pedro the possibility of caching the mask register values -(which are per-process and can change mid-execution), but there isn't a good -spot to cache those values. Besides, the mask registers can change constantly -for bare-metal debugging when switching between exception levels. - -In some cases, it is just not possible to get access to these mask registers, -like the case where threads are running. In those cases, using a default mask -to remove the non-address bits should be enough. - -This can happen when we let threads run in the background and then we attempt -to access a memory address (now that gdb is capable of reading memory even -with threads running). Thus gdb will attempt to remove non-address bits -of that memory access, will attempt to access registers, running into errors. - -Regression-tested on aarch64-linux Ubuntu 20.04. ---- - gdb/aarch64-linux-tdep.c | 64 ++++++++++++++++++++++++++++++---------- - 1 file changed, 49 insertions(+), 15 deletions(-) - -diff --git a/gdb/aarch64-linux-tdep.c b/gdb/aarch64-linux-tdep.c -index 20a041c599e..4b2915b8e99 100644 ---- a/gdb/aarch64-linux-tdep.c -+++ b/gdb/aarch64-linux-tdep.c -@@ -57,6 +57,9 @@ - #include "elf/common.h" - #include "elf/aarch64.h" - -+/* For inferior_ptid and current_inferior (). */ -+#include "inferior.h" -+ - /* Signal frame handling. - - +------------+ ^ -@@ -1986,29 +1989,60 @@ aarch64_linux_decode_memtag_section (struct gdbarch *gdbarch, - static CORE_ADDR - aarch64_remove_non_address_bits (struct gdbarch *gdbarch, CORE_ADDR pointer) - { -- aarch64_gdbarch_tdep *tdep = gdbarch_tdep<aarch64_gdbarch_tdep> (gdbarch); -- - /* By default, we assume TBI and discard the top 8 bits plus the VA range -- select bit (55). */ -+ select bit (55). Below we try to fetch information about pointer -+ authentication masks in order to make non-address removal more -+ precise. */ - CORE_ADDR mask = AARCH64_TOP_BITS_MASK; - -- if (tdep->has_pauth ()) -+ /* Check if we have an inferior first. If not, just use the default -+ mask. -+ -+ We use the inferior_ptid here because the pointer authentication masks -+ should be the same across threads of a process. Since we may not have -+ access to the current thread (gdb may have switched to no inferiors -+ momentarily), we use the inferior ptid. */ -+ if (inferior_ptid != null_ptid) - { -- /* Fetch the PAC masks. These masks are per-process, so we can just -- fetch data from whatever thread we have at the moment. -+ /* If we do have an inferior, attempt to fetch its thread's thread_info -+ struct. */ -+ thread_info *thread -+ = find_thread_ptid (current_inferior ()->process_target (), -+ inferior_ptid); - -- Also, we have both a code mask and a data mask. For now they are the -- same, but this may change in the future. */ -- struct regcache *regs = get_current_regcache (); -- CORE_ADDR cmask, dmask; -+ /* If the thread is running, we will not be able to fetch the mask -+ registers. */ -+ if (thread != nullptr && thread->state != THREAD_RUNNING) -+ { -+ /* Otherwise, fetch the register cache and the masks. */ -+ struct regcache *regs -+ = get_thread_regcache (current_inferior ()->process_target (), -+ inferior_ptid); -+ -+ /* Use the gdbarch from the register cache to check for pointer -+ authentication support, as it matches the features found in -+ that particular thread. */ -+ aarch64_gdbarch_tdep *tdep -+ = gdbarch_tdep<aarch64_gdbarch_tdep> (regs->arch ()); -+ -+ /* Is there pointer authentication support? */ -+ if (tdep->has_pauth ()) -+ { -+ /* We have both a code mask and a data mask. For now they are -+ the same, but this may change in the future. */ -+ CORE_ADDR cmask, dmask; - -- if (regs->cooked_read (tdep->pauth_reg_base, &dmask) != REG_VALID) -- dmask = mask; -+ if (regs->cooked_read (tdep->pauth_reg_base, &dmask) -+ != REG_VALID) -+ dmask = mask; - -- if (regs->cooked_read (tdep->pauth_reg_base + 1, &cmask) != REG_VALID) -- cmask = mask; -+ if (regs->cooked_read (tdep->pauth_reg_base + 1, &cmask) -+ != REG_VALID) -+ cmask = mask; - -- mask |= aarch64_mask_from_pac_registers (cmask, dmask); -+ mask |= aarch64_mask_from_pac_registers (cmask, dmask); -+ } -+ } - } - - return aarch64_remove_top_bits (pointer, mask); --- -2.34.1 - |